JP2008077709A - Objective lens actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an objective lens actuator which can easily be attached to a movable part of an elastic supporting member. <P>SOLUTION: An objective lens 26 is held by a lens holder 27. Driving coils 28, 19 for generating focusing thrust and tracking thrust are provided in the lens holder 27, In order to support the lens holder 27 so as to be displaced in accordance with thrust generation quantity of the driving coils 28, 29, a plurality of supporting springs 30a, 30b the one end of which is connected to both side planes of the lens holder 27 are provided at a supporting plane of a difference in level state or a tilt state so that connection height is different in the focus direction keeping a parallel state of the supporting springs 30a, 30b in respective planes of both side planes of the lens holder 27. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an objective lens actuator that performs focusing control and tracking control on an objective lens.

  Conventionally, an objective lens actuator that is used in an optical pickup device or the like and performs focusing control and tracking control on an objective lens is one that controls the objective lens to a desired position at high speed by electrical direct modulation of a drive coil. It is general (see, for example, Patent Document 1).

  In order to satisfy this, the movable part including the lens holder holding the objective lens is lightweight, the structure of the movable part is highly rigid so that it does not deform internally due to high-speed movement, etc. It is necessary that the structure and components of the unit endure the heat generated by the power consumption of the drive coil, and the Abbe principle must be satisfied as the principle necessary for the structure of the precision drive mechanism.

  Abbe's principle is that the driving force is movable for low-frequency driving characteristics so that the movable part does not tilt when it is desired to translate, or the opposite event does not occur. It is necessary to act on the center of the support spring that supports the part. For high-frequency driving characteristics, the driving force needs to act on the center of inertia of the movable part.

  In other words, in the case of an objective lens actuator, the thrust center of the drive coil, the elastic center of the support spring that supports the movable portion, and the inertia center of the mass distribution need to match.

  FIG. 3 shows an example of a conventional objective lens actuator, in which (A) is a front view of the objective lens actuator, (B) is a side view of the objective lens actuator, and (C) is a bottom view of the objective lens actuator. In FIG. 3A, the vertical direction on the paper is the tangential direction on the optical disc, the orthogonal direction on the paper is the focus direction, and the horizontal direction on the paper is the radial direction (tracking direction). In the following description, the vertical and horizontal directions will be described with reference to FIG.

  In FIG. 3, reference numeral 1 denotes a stator portion mounted on an optical information recording / reproducing apparatus such as an optical pickup apparatus.

  The stator portion 1 includes a substantially rectangular base body 2, magnets 3 a and 3 b that are fixed to one surface of yokes 2 a and 2 b that are spaced apart above and below the base body 2, and the magnet 3 a. And a magnet 5b, and a mount 5 fixed to the other surface of the upper yoke 2a.

The movable portion 4 includes a lens holder 7 that holds the objective lens 6, a focusing drive coil 8, a tracking drive coil 9, and a plurality of (four in this example) support springs penetrating the mount 5 at one end. 10 and a printed wiring board 11 for feeding a support spring and driving coil for fixing the other end of the support spring 10 by soldering, which serves both as mechanical coupling and electrical coupling, and to the back surface of the lens holder 7. And an inertia ballast 12 for mainly canceling the inertial moment of inertia of the objective lens 6. Note that one end of the support spring 10 is connected and fixed to a flexible printed wiring board 13 provided on the mount 5 by soldering that serves both as mechanical coupling and electrical coupling.
Japanese Patent No. 3754225 JP 2006-134437 A

  By the way, in the objective lens actuator configured as described above, since the distance between the support springs 10 in the radial direction is constant regardless of the height in the focus direction, the structure is highly symmetrical. In particular, since the support spring 10 on the lower side in the focus direction is disposed very close to the base, there is a problem that the structure is unsuitable for highly accurate assembly.

  In particular, when the support spring 10 is connected to the printed wiring board 11 by soldering so as to require electrical conductivity, this disadvantage is great, and any radial side is disposed below the focus direction. Since the support spring 10 is close to the base portion 1, there is a problem that it is difficult to solder to the printed wiring board 11, and the degree of freedom in setting the translational and rotational resonance frequencies and component placement is also low. There was a problem.

  Further, in order to correct the center of inertia shift due to the first moment of inertia of the objective lens 6 attached to the upper end of the movable portion 4, it is necessary to consider such as attaching the inertia ballast 12 on the lower side and increasing the volume of the lens holder 7. Therefore, the lower support spring arrangement dimension on the lower side of the movable part 4 is liable to be problematic as the upper side is less flexible.

  Further, Patent Document 2 describes an example in which three support springs 10 shown in FIG. 3A are arranged on the left and right sides, and the movable part side fixed end located at the center is extended. The workability of the spring is poor, and, for example, the wiring pattern formation of the printed wiring board 11 is complicated by shifting the connecting portion from the other two by one, and it is avoided that the soldering interval is narrow. The problem of not being able to be solved could not be solved.

  The present invention has been made in view of the above background, and an object thereof is to provide an objective lens actuator capable of easily attaching an elastic support member to a movable portion.

  The objective lens actuator according to claim 1, which is made according to the present invention to solve the above-mentioned problems, includes a lens holder that holds the objective lens, a drive coil that is provided on the lens holder and generates a focusing thrust and a tracking thrust, An objective lens actuator comprising: a plurality of elastic support members having one ends connected to both side surfaces of the lens holder in order to displaceably support the lens holder in accordance with a thrust generation amount of the drive coil. A stepped or inclined support surface is provided on each of the two side surfaces so that the connection height differs in the focus direction while maintaining the parallel state of the elastic support member.

  According to a second aspect of the present invention, in the objective lens actuator according to the first aspect of the present invention, the radial spacing when paired with the elastic support member facing the both surfaces of the lens holder is the objective in the focus direction. The distance between the pair located on the lens side is narrower and the distance is wider as the distance from the objective lens is increased.

  According to a third aspect of the present invention, there is provided the objective lens actuator according to the first or second aspect, wherein three or more of the elastic support members are arranged and the distance in the focus direction between pairs adjacent in height in the focus direction. Is constant in any pair, and the difference in the radial interval between adjacent pairs is constant in any adjacent pair.

  According to a fourth aspect of the present invention, in the objective lens actuator according to the third aspect, the pair of substrates fixed to the support surface and electrically connected to the drive coil are positioned on the side surfaces in the radial direction. It is characterized by being fixedly tilted with respect to the focus axis so as to be equidistant from all the elastic support members.

  As described above, according to the objective lens actuator of the first aspect of the present invention, all the conductive springs remain in a parallel arrangement, and the radial distances between pairs having different heights in the focus direction are different. Therefore, it is possible to increase the degree of freedom in setting the design layout and resonance frequency while maintaining a structure that does not cause undesired parasitic motion. Therefore, the elastic support member can be easily attached to the movable part.

  According to the second aspect of the present invention, the radial distance between the spring pairs is arranged such that the distance between the spring pair on the disk side in the focus direction is narrower and the distance is larger as the distance from the disk side is larger. Since the nearest lower support spring can be disposed outside the side surface, easy and highly accurate assembly is possible.

  According to the third and fourth aspects of the present invention, the distance in the focus direction between adjacent pairs in which the height in the focus direction is adjacent is constant in any pair, and the difference in radial dimension between the pairs in which the height in the focus direction is adjacent. However, since every adjacent pair is constant, and the pair of relay boards is fixed at an angle with respect to the focus axis so as to be equidistant from all the conductive springs located on the side surfaces in the radial direction, It is possible to arrange the board avoiding the necessary parts and shape under the movable part of the high-function actuator, and easy and highly accurate assembly is possible because the distance between all the springs and the board is constant. . Further, even if the actuator is thinned in the focus direction, the substrate is mounted with an inclination, so that the distance between the support springs is clearly wider than that of the conventional example, which is advantageous for forming the pattern of the substrate.

  Next, an objective lens actuator according to an embodiment of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 shows Embodiment 1 of the objective lens actuator of the present invention. FIG. 1 (A) is a front view of the objective lens actuator, FIG. 1 (B) is a side view of the objective lens actuator, and FIG. It is a bottom view of a lens actuator. In FIG. 1A, the vertical direction on the paper is the tangential direction on the optical disc, the orthogonal direction on the paper is the focus direction, and the horizontal direction on the paper is the radial direction (tracking direction). Moreover, in the following description, it demonstrates on the basis of the up-down-left-right direction of this FIG. 1 (A).

In FIG. 1, reference numeral 21 denotes a stator portion mounted on an optical information recording / reproducing apparatus.
The stator portion 21 includes a substantially rectangular base body 22 as a support member, and magnets 23a and 23b fixed to the mutually opposing surfaces of yokes 22a and 22b provided in a separated state above and below the base body 22 in the figure. The movable portion 24 disposed between the magnet 23a and the magnet 23b and the mount 25 fixed to the other surface of the yoke 22a are provided.

  The movable portion 24 includes a lens holder 27 that holds the objective lens 26, a focusing drive coil 28, a tracking drive coil 29, and a plurality of elastic mounts (one total of four in this example) penetrating the mount 25 at one end. A support spring 30 as a member, a support spring fixing and driving coil feeding printed wiring boards 31a and 31b for fixing the other end of the support spring 30 by soldering which serves both as mechanical coupling and electrical coupling, and a lens holder 27, and an inertia ballast 32 that is fixed to the back surface of the objective lens 27 and mainly cancels the inertial moment of inertia of the objective lens 26.

  In addition, the movable portion 24 is configured such that the operation center and the optical axis of the objective lens 26 coincide with each other. One end of the support spring 30 penetrating the mount 25 is connected and fixed by a flexible printed wiring board (not shown) provided in the mount 25 or by soldering that combines mechanical coupling and electrical coupling to pattern formation. ing. At this time, a damper material (not shown) for damping vibration is embedded in the mount 25 so as to wrap the support spring 30.

  The focusing drive coil 28 and the tracking drive coil 29 are electrically connected to a printed wiring board 31 for fixing the support spring and feeding the drive coil.

  Further, in the present embodiment, the support spring 30 is a metal wire spring, and as the fixing method, the printed wiring boards 31a and 31b for fixing the support spring and feeding the drive coil serve both as mechanical coupling and electrical coupling. Soldering. The printed circuit boards 31a and 31b are formed on both side surfaces of the lens holder 27, and support surfaces 27a formed in a step shape so that the support springs 30a and 30b on the lower side in the focus direction protrude outward in the radial direction. Is provided.

  In this structure, it is easy to solder the support springs 30a and 30b on the lower side in the focus direction, and the degree of freedom of the shape structure of the inertia ballast 32 attached to the lower side of the structure is increased. Further, it is possible to increase the torsional rigidity with respect to the inclination of the movable portion 4 in the radial direction as compared with the conventional example.

(Embodiment 2)
FIG. 2 shows Embodiment 2 of the objective lens actuator of the present invention. FIG. 2 (A) is a front view of the objective lens actuator, FIG. 2 (B) is a side view of the objective lens actuator, and FIG. It is a bottom view of a lens actuator. In FIG. 2, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In the second embodiment, a case where a triaxial drive actuator having a radial tilt function is configured is shown, and three pairs of support springs 40a, 40b, and 40c having the same height in the focus direction are adjacent to each other by the same amount. This is an example in which the interval is widened in the radial direction.

  In this example, an inclined support surface 27b is formed on each side surface of the lens holder 27 so that the connection height differs in the focus direction while maintaining the parallel state of the support springs 40a, 40b, and 40c. Yes. By arranging the printed wiring board 41 on the support surface 27b, the support springs 40a, 40b, 40c are arranged in three or more pairs, and the distance in the focus direction between pairs whose heights are adjacent in the focus direction is constant in any pair. In addition, the difference in radial distance between adjacent pairs in the height in the focus direction is constant in any adjacent pair.

  In addition, a pair of substrates 41, 41 fixed to the support surface 27b and electrically connected to the focusing drive coil 28 and the tracking drive coil 29 are all the support springs 40a, 40a located on the side surfaces in the radial direction. Inclined and fixed with respect to the focus axis so as to be equidistant from 40b and 40c.

  According to the objective lens actuator having such a structure, the printed wiring board 41 can be inclined and arranged parallel to the line connecting the cross-sectional centers of the support springs, so that the support springs 40a, 40b, The soldering workability of 40c can be further improved.

  The objective lens actuator of the present invention is a lens actuator mounted on an optical disc recording / reproducing pickup, and is an actuator capable of biaxial translational driving in the focus direction and the radial direction as described above. For example, in addition to this 2-axis translation drive, an actuator capable of 3-axis to 4-axis drive including radial axis and tangential axis tilt correction, a drive coil for at least 2-axis drive for this drive, Of course, the present invention can be applied to an actuator or the like in which a driving coil for driving three to four axes is mounted on a movable portion.

1 shows Embodiment 1 of an objective lens actuator of the present invention, in which (A) is a front view of the objective lens actuator, (B) is a side view of the objective lens actuator, and (C) is a bottom view of the objective lens actuator. Embodiment 2 of the objective lens actuator of the present invention is shown, (A) is a front view of the objective lens actuator, (B) is a side view of the objective lens actuator, and (C) is a bottom view of the objective lens actuator. A conventional objective lens actuator is shown, (A) is a front view of the objective lens actuator, (B) is a side view of the objective lens actuator, and (C) is a bottom view of the objective lens actuator.

Explanation of symbols

24 ... Moving part 26 ... Objective lens 27 ... Lens holder 27a, b ... Support surface 28 ... Focusing drive coil 29 ... Tracking drive coil 30a ... Support spring (elastic support member)
30b ... Support spring (elastic support member)
32 ... Inertial ballast

Claims (4)

A lens holder for holding the objective lens, a drive coil provided on the lens holder for generating a focusing thrust and a tracking thrust, and one end for supporting the lens holder in a displaceable manner according to the amount of thrust generated by the drive coil. A plurality of elastic support members connected to both side surfaces of the lens holder, and an objective lens actuator comprising:
A stepped or inclined support surface is provided on each side surface of the lens holder so that the connection height differs in the focus direction while maintaining the parallel state of the elastic support member. Lens actuator.   When the pair of elastic support members that are opposed to each other on both surfaces of the lens holder are paired such that the radial distance between them is closer to the objective lens side in the focus direction, the distance is narrower and the distance is further away from the objective lens. The objective lens actuator according to claim 1, wherein:   Three or more elastic support members are arranged and the distance in the focus direction between the pairs whose heights are adjacent in the focus direction is constant in any pair, and the distance in the radial direction between the pairs whose heights in the focus direction are adjacent to each other The objective lens actuator according to claim 1, wherein a dimensional difference is constant in any adjacent pair.   A pair of substrates fixed to the support surface and electrically connected to the drive coil is inclined with respect to the focus axis so as to be equidistant from all elastic support members positioned on the side surfaces in the radial direction. The objective lens actuator according to claim 3, wherein the objective lens actuator is fixed.

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